Demo Use JCasC to Create Jobs

In this lesson, you’ll learn how to leverage the Jenkins Configuration as Code (JCasC) plugin to define pipeline jobs, manage global settings, and install build tools—all through YAML. We’ll explore official demos, customize configurations, and apply them in your Jenkins instance.

Prerequisites

• Jenkins with Configuration as Code plugin installed
• Access to Jenkins controller shell
• Basic familiarity with YAML and Jenkins plugins

1. Explore Example Configurations

The JCasC plugin demos on GitHub contain ready-made use cases:

2. Configure Global Authorization

To set up a matrix-based authorization strategy, add the following to your jenkins-casc.yaml:

jenkins:
  authorizationStrategy:
    globalMatrix:
      permissions:
        - "USER:Overall/Read:anonymous"
        - "GROUP:Overall/Administer:authenticated"
        - "USER:Overall/Administer:admin"

3. Configure a Kubernetes Cloud

Click Config YAML under the Kubernetes demo to copy this snippet:

unclassified:
  location:
    url: http://jenkins/

jenkins:
  clouds:
    - kubernetes:
        name: "advanced-k8s-config"
        serverUrl: "https://advanced-k8s-config:443"
        serverCertificate: "serverCertificate"
        skipTlsVerify: true
        credentialsId: "advanced-k8s-credentials"
        namespace: "default"
        jenkinsUrl: "http://jenkins/"
        jenkinsTunnel: "JenkinsTunnel"
        containerCapStr: 42
        maxRequestsPerHostStr: 64
        retentionTimeout: 5
        connectTimeout: 10

4. Install Build Tools

You can also install Node.js, Git, Maven, and SonarQube Scanner using JCasC. Here’s an example for Node.js:

tool:
  nodejs:
    installations:
      - name: "NodeJS Latest"
        home: ""  # required until nodejs-1.3.4 release (JENKINS-57508)
        properties:
          installSource:
            installers:
              - nodeJSInstaller:
                  id: "12.11.1"
                  npmPackagesRefreshHours: 48  # default is 72

Tool Installation Summary

5. Edit Your jenkins-casc.yaml

On the controller, open or create your configuration file:

cd /var/lib/jenkins/JENKINS_BACKUP
vi jenkins-casc.yaml

A comprehensive file may include credentials, SCM settings, tool definitions, and more:

credentials:
  system:
    domainCredentials:
      - usernamePassword:
          description: 'Gitea Server Credentials'
          id: gitea-server-creds
          username: gitea-admin
          password: '{AQAAB...}'
          scope: GLOBAL
      - usernamePassword:
          description: 'Credentials for MongoDB'
          id: mongo-db-credentials
          username: superuser
          password: '{AQAAB...}'
          scope: GLOBAL
      - string:
          description: 'Mongo Database Username'
          id: moneo-db-username

git:
  installations:
    - home: "git"
      name: "Default"

maven:
  installations:
    - name: "M398"
      properties:
        - installSource:
            installers:
              - maven:
                  id: "3.9.8"

sonarRunnerInstallation:
  installations:
    - name: "sonarqube-scanner-610"
      properties:
        - installSource:
            installers:
              - sonarRunnerInstaller: {}

6. Define Pipeline Jobs with Job DSL

In the demos folder, there’s a sample that uses the Job DSL plugin to create a folder and pipeline job:

Add these job definitions to your jenkins-casc.yaml:

jobs:
  - script: >
      folder('test-jobs')
  - script: >
      pipelineJob('test-jobs/default-agent') {
        definition {
          cps {
            script("""
              pipeline {
                agent any
                stages {
                  stage('test') {
                    steps {
                      echo 'hello'
                    }
                  }
                }
              }
            """.stripIndent())
          }
        }
      }

7. Reload Configuration and Troubleshoot

After saving, go to Manage Jenkins → Configuration as Code → Reload Existing Configuration. You may see:

To resolve:

1. Manage Jenkins → Manage Plugins
2. Search for Job DSL and install.
3. Reload or reapply your JCasC configuration.

8. Verify Jobs and Tools

Once the DSL plugin is active, Jenkins will create the test-jobs folder and the default-agent pipeline automatically. You can also confirm tool installations under Manage Jenkins → Global Tool Configuration:

pipeline {
  agent any
  stages {
    stage('test') {
      steps {
        echo "Hello"
      }
    }
  }
}

References

• Configuration as Code Plugin
• Job DSL Plugin
• Kubernetes Cloud
• NodeJS Plugin
• Maven Integration Plugin